Asphalt plastisols



Dec. 26, 1967 "w CORBETT ET AL 3,360,455

' SPHALT PLASTISQLS Filed Jan. 27, 1966' DISTILL ATlON ASPHAlI FEEDn-HEPTANE 7 n-HEPTANE .STORAGE TO STORAGE i FLASH TOWER ll MIXING 'HEADI coouwe VESSEL 25 v .20 Y CENTRlFUG E l 27 2s- A H 12' n-HEPTANE 17 TOSTORAGE I/ZB l3 4 1 i V/ I5 PULVERIZER FLASH TOWER MIXING VESSEL MIXINGvE ssEL ASPHALT PLASTlSOL 32 A LUKE W. CORBETT ROBERT E. SWARBRICKIINVENTORS PATENT ATTORNEY United States Patent 3,360,455 ASPHALTPLASTISOLS Luke W. Corbett, Mountainside, and Robert E. Swarbrick,

Belle Mead, N.J., assignors to Esso Research and Engineering Company, acorporation of Delaware Filed Jan. 27, 1966, Ser. No. 523,299 5 Claims.(Cl. 20822) ABSTRACT OF THE DISCLOSURE Asphalts are fractionated intoasphaltenes, high molecular weight petrolenes and low molecular weightpetrolenes. The high molecular weight petrolene fraction is coated withthe asphaltene fraction and thereafter suspended in the low molecularweight petrolene fraction to form a stable asphalt plastisol.

This invention relates to asphalt compositions having improved flowproperties and more particularly to stable asphalt plastisols and theirpreparation.

The general method used in preparing hot-mix pavements is by preheatingmineral aggregate to approximately 325 F. and coating this aggregatewith asphalt ranging in softening point from about 105 F. up to about140 F. This asphalt is also preheated to approximately 300 P. so that itwill effectively spread over the mineral particle surfaces. Thepractical difiiculties encountered with this general method are thelarge amounts of heat that must be employed in order to fluidize theasphalt binder and the inherent problems encountered in storing andtransferring the asphalt in this fluid condition.

Thus, it is a primary object of this invention to provide useful asphaltcompositions which are fluid and of low viscosity at ordinary ambienttemperatures and which can be easily stored, transferred and mixedwithout the application of large amounts of heat.

The present invention is predicated on the discovery that asphalt can beseparated into several fractions which can subsequently be recombined ina particular manner to form a stable asphalt plastisol havingsubstantially improved ilow properties and which can be used in the sameapplication as the original asphalt composition. As is well known in theart, asphalt can be regarded as comprising two general components, i.e.,petrolenes and asphaltenes. The asphaltenes are distinguished from thepetrolenes in that asphaltenes have a much higher molecular weight, ahigher boiling point and are higher in aromaticity. Both materials arethemselves mixtures of hydrocarbons and their heteroatom analogs.

In accordance with this invention, asphalt compositions are renderedfluid by a process comprising the necessary steps of: (l) admixingasphaltenes and nonvolatile petrolene particles having an initialatmospheric boiling point within the range between about 600 F. and 1400F. to form asphaltene-coated nonvolatile petrolene particles and (2)admixing the said coated particles with liquid volatile petrolenes toproduce an asphalt plastisol.

When starting with atypical asphalt feed, an embodiment of thisinvention comprises (1) distilling the asphalt at elevated temperaturesand reduced pressures to separate the lower boiling fractions, i.e., thevolatile petrolenes, from the nonvolatile fraction comprised ofasphaltenes and nonvolatile petrolenes and having an initial boilingpoint within the range between 600 and 1400 F., (2) contacting thenonvolatile fraction with a liquid parafiin to precipitate theasphaltenes and form an asphaltene fraction and a nonvolatile petrolenefraction, (3) separating said asphaltene fraction from said nonvolatilepetrolene fraction, (4) removing said liquid ice parafiin from saidasphaltene fraction and said nonvolatile petrolene fraction, (5) coolingthe said nonvolatile petrolene fraction, (6) pulverizing the said coolednonvolatile petrolene fraction, (7) admixing the said asphaltenes andsaid pulverized nonvolatile petrolenes to form asphaltene-coatednonvolatile petrolene particles and (8) admixing the said coatedparticles with the said volatile petrolenes to produce an asphaltplastisol.

The invention will be more fully understood by referring to FIGURE 1which shows a flow diagram of one embodiment of the same.

While the process of the present invention may be employed to fiuidizeasphalts, residua, heavy fuel oils and the like, it has specialapplication to asphalts. The present invention contemplates theemployment of any asphalt composition comprising petrolenes andasphaltenes. The asphalt composition is not critical because nomodification of the composition is produced by the practice of thepresent invention but rather what is accomplished is the physicalmodification of the asphalt in such a manner that its flow propertiesare vastly improved. Illustrative of this is the fact that a solidasphalt paving binder can be processed according to the presentinvention to yield a fluid, low viscosity asphalt paving binder whichcan subsequently be added to the hot mineral aggregate to produce anasphalt pavement having the same properties as would be obtained by theuse of the hot mineral aggregate with the norm-ally solid asphalt pavingbinder. Broadly, the asphalts which are operable in the concept of thisinvention may contain from about 20 to about 60 wt. percent volatilepetrolenes, from about 10 to about 50 wt. percent nonvolatile petrolenes(i.e., those petrolenes having an initial boiling point within the rangebetween 600 and 1400 F.) and from about 5 to about 40 wt. percentasphaltenes. Nonlimiting examples of asphalts which may be employed arestraight reduced asphalts, air blown asphalts and blended asphaltshaving the foregoing compositions. The asphalts may be, for example,derived from Lagunillas, Boscan, Aramco, Talco, Kuwait, Oregon Basin,Lloydminster, Santa Maria, Kern River, and Eucutta crudes and the like.In addition, the asphalt plastisol may be formulated from the totalamount of materials fractionated from the asphalt or it may beformulated from only a portion of the materials fractionated provided,however, that the resultant product composition is within thebeforementioned operable range.

The precipitant used to separate asphaltenes from the nonvolatilepetrolenes includes any liquid parafiin which, when contacted wtih apetroleum fraction containing asphaltenes, causes said asphaltenes toprecipitate as solids. Such precipitants are well known in the art,e.g., US. Patent 3,087,887, which is incorporated herein by reference.Such precipitants include the C to C par-afiins, preferably thesaturated C to C normal paraffins. Nonlimiting examples of suitableprecipitants are n-pentane, n-hexane, n-hexane, isooctane, dodecane andthe like.

The asphalt is fed into a distillation zone where the volatilepetrolenes are separated in accordance with known techniques from thenonvolatile fraction comprising nonvolatile petrolenes and asphaltenes.The temperature and pressure employed will depend upon the particularasphalt which is to be fractionated. In general, asphalts having higherboiling points will require lower distillation pressures and/0r higherdistillation temperatures. Broadly, the conditions used include atemperature of from about 400 to about 800 F. and a pressure less thanatmospheric, i.e., between about .1 and about 50 mm. of mercuryabsolute. It is preferred, however, that the temperature be less than750 F. and the pressure be less than 2 mm. Hg. Temperatures in excess of800 F. should be avoided in order to minimize any possible thermaldegradation of the asphalt. The temperature, pressure and time in thedistillation zone should be adjusted so that the initial atmosphericboiling point of the nonvolatile fraction (i.e., the distillationbottoms) which is withdrawn will be within the range between about 600and 1400 F. The boil 'ing point range of the volatile petrolenes (i.e.,the distillation overhead) will be, of course, within the range betweenthe initial boiling point of the asphalt feed and the initial boilingpoint of the aforedescribed nonvolatile fraction.

The nonvolatile fraction recovered from the distillation zone iscontacted with the aforedescribed liquid paraffin into which asphaltenesprecipitate as solids. The temperatures and pressures used may varywidely. It has been found that this separation can be convenientlyeffected at a temperature of from about 50 to about 200 F. and atatmospheric pressure. Contact time is not critical since upon contact ofthe nonvolatile fraction with the liquid paraffin, precipitation of theasphaltenes as solids is very rapid. The precipitated asphaltenefraction is then subsequently removed from the petrolene fraction byfiltration or by centrifugation, preferably the latter. The separatedasphaltene fraction and the nonvolatile petrolene fraction are thenseparately treated in order to isolate the respective products. Forexample, the separated asphaltenes may be dried in air at ambienttemperatures or at elevated temperatures (e.g., 150 F.) under inertatmosphere. The separated petrolenes may be conveniently recovered fromsolution by distilling off the liquid paraifin at a temperature of 100to 175 F. and a pressure of 25 to 100 mm. Hg absolute.

The nonvolatile petrolenes recovered from the liquid paraffin solutionare cooled to temperatures below about 60 F., preferably below about 40F., and pulverized at this temperature to pass a number 8 US. StandardSieve screen. Nonvolatile petrolene particles of from about number 200to about number 8 US. Standard Sieve size have been found to beparticularly effective in the concept of this invention.

In accordance with this invention the cooled nonvolatile petrolenes areadmixed after pulverizing with asphaltenes until the surface of thenonvolatile petrolene particles are coated with the dust-likeasphaltenes. The asphaltenes, being essentially infusible and dust-like,tend to coat or dust the surface of the ground petrolenes. This coatingtechnique is desirable to prevent coalescing of the nonvolatilepetrolene particles. The foregoing pulverizing and mixing operations canbe effected in any conventional equipment such as a pulverizing mill ora ball mill. The asphaltene-nonvolatile petrolene blend is subsequentlyadmixed at ambient temperatures (e.g.,' 60100 F.) with the volatilepetrolenes which being liquid act as a plasticizer and produce anasphalt plastisol, i.e., a dispersion of a finely divided solid in aliquid. Broadly, these asphalt plastisols comprise from about 10 toabout 50 wt. percent nonvolatile petrolenes, from about to about 40 Wt.percent asphaltenes and from about 20 to about 60 wt. percent volatilepetrolenes. It is preferred, however, that they comprise from about 15to about 30 wt. percent nonvolatile petrolenes, from about 20 to about35 wt. percent asphaltenes and from about 35 to about 50 wt. percentvolatile petrolenes.

Turning now to the figure, a straight reduced residuum from a Venezuelancrude having an ASTM softening point of 115 R, an ASTM penetration 77 F.of 90; and composed of 84 wt. percent petrolenes and 16 wt. percentasphaltenes is used as the feed in the specific embodiment to bedescribed hereinafter. The feed is heated to 270 F. and pumped throughline 1 into distillation vessel 2 which may be a vacuum pipestill. Thetemperature and pressure employed are approximately 700 F. and 5 mm. Hgabsolute respectively. The low boiling material, i.e., the volatilepetrolenes, are taken off overhead through line 3 and condensed incondenser 4 at about 180 F. and then pumped through line 5 into mixingvessel 31.

The bottoms from vessel 2, i.e., the nonvolatile fraction comprisingasphaltenes and nonvolatile petrolenes and having an initial boilingpoint of about 1150 F., are withdrawn through line '6 as a liquid atabout 500 F., cooled in heat exchanger 7 to about 300 F., and thenpassed through line 8. Liquid normal heptane from storage 9 111 anamount sufiicient to precipitate the asphaltenes is then pumped via line10 into contact with the nonvolatile fraction in line 8. The mixtureratio is preferably 12/1 of normal heptane to nonvolatile fraction byvolume, although this may vary from about 4/1 to 50/ 1. Other liquidparaffins as hereinbefore mentioned may be used in place of normalheptane. The mixture is then passed through a mixing head 11 or someother suitable mixing device and thence into a continuous type highspeed centrifuge 12 wherein the precipitated asphaltenes are separatedfrom the nonvolatile petrolene-hexane solution. The asphaltene-hexaneslurry rejected from the centrifuge is then continuously pumped throughline 13 into heat exchanger 14 wherein it is heated to about 250 F. andthence to flash tower 16 by means of line 15 for stripping atatmospheric pressure. Normal heptane is taken overhead through line 17,subsequently condensed and sent to storage. The bottoms from flash tower16, i.e. the asphaltenes, are withdrawn as solids via line 18 and sentto mixing vessel 19. The nonvolatile petrolenes from centrifuge 12 arewithdrawn through line 20, heated in heat exchanger 21 to about 250 F.and sent to flash tower 23 via line 22 wherein normal heptane is takenoverhead through line 24 for reuse and the nonvolatile petrolene bottomsis withdrawn through line 25. The nonvolatile petrolenes are then cooledto about 20 F. in cooling vessel 26 and then conveyed as solids via line27 to pulverizer 28 which may be a rod mill or ball mill. The groundnonvolatile petrolenes are then sent by means of line 29 into mixingvessel 19 for admixture with the asphaltenes at a temperature of about20 F. The solid asphaltenenonvolatile petrolene blend is sent via line30 into mixing vessel 31 wherein it is combined at 75 F. with thevolatile petrolenes to yield an asphalt plastisol comprising 51 wt.percent nonvolatile petrolenes, 16 wt. percent asphaltenes and 33 wt.percent volatile petrolenes.

The invention can more fully be understood by reference to the followingexamples.

Example 1 An asphalt, i.e., a straight reduced Venezuelan crude Ollresiduum, having an ASTM softening point of F. and a viscosity at 77 F.of 6.5 1O poises, was processed according to the process illustrated inthe figure. The yield of the fractions separated from the asphalt werebased on the total weight of the asphalt fractionated, 44 wt. percentvolatile petrolenes, 13 wt. percent asphaltenes and 43 wt. percentnonvolatile petrolenes. These materials were combined in accordance withthis inventlon to form an asphalt plastisol having an ASTM softeningpoint of 50 F. This asphalt plastisol was then combmed with a mineralaggregate commonly used in paving, i.e., an Asphalt Institute type VIagraded aggregate. This was done by the conventional hot-mix methodexcept that the aggregate was heated to 400 F. and the binder was addedcold as a plastisol rather than as a hot asphalt liquid. After mixingfor 5 minutes, Marshall briquets were prepared and tested by theMarshall test method The original solid asphalt was also combined withthe aforedescribed mineral aggregate by the conventional hotmix process,i.e., both the nonplastisol asphalt and the mineral aggregate were.preheated prior to admixture. This admixture was also tested by theMarshall test method. The comparative test results for test specimenscontaining 6.5 Wt. percent of the plastisol or nonplastisol and 93.5 wt.percent of the aforedescribed aggregate are shown in Table I. It is seenfrom the foregoing and Table I that the practice of the presentinvention results in a substantial improvement in the asphalt fluiditywithout any TABLE I.MARSHALL TEST Binder Used Nonplastisol AsphaltAsphalt Plastisol Voids, percent 6.0 6. Marshall Stability 140 F., lbs760 750 Marshall Flow 140 F., .01 10 10 l ASTM D 155962T=Test forResistance to Plastic Flow of Bituminous Mixtures Using MarshallApparatus.

Example 2 As hereinbefore mentioned, asphalt plastisols may beformulated from the total amount of materials fractionated from theasphalt, as in Example 1, or they may be formulated from only a portionof the fractions separated. The latter procedure has the advantage thatthe performance properties can be improved by the proper selection ofthe amounts of materials to be combined to yield the plastisol. Portionsof the separated volatile petrolenes, asphaltenes and nonvolatilepetrolenes from Example 1 were combined to formulate a plastisolconsisting of 47 /2 wt. percent volatile petrolenes, 38 wt. percentasphaltenes and 14 /2 wt. percent nonvolatile petrolenes. The resultantplastisol had an ASTM softening point of 60 F. and a viscosity at 77 F.of 7.8)(10' poise. A portion of this plastisol was then fluxed at 400 F.to break down the plastisol and to yield a nonplastisol asphalt havingthe same composition of the plastisol. This nonplastisol asphalt had asoftening point of 108 F. and a viscosity at 77 F. of 1.4 1O poise. Asin Example 1, Marshall briquets were prepared from both the asphaltplastisol and the solid nonplastisol asphalt. The comparative testresults for test specimens containing 6.5 wt. percent of the plastisolor nonplastisol and 93.5 wt. percent of an Asphalt Institute type VIaggregate are shown in Table II. It is again seen that the fluidity ofthe asphalt has been substantially improved without any detrimentaleffect on the asphalt performance properties.

TABLE IL-MARSHALL TEST Binder Used Nonplastisol Asphalt AsphaltPlastisol Voids, percent 3. 3. 2 Marshall Stability 140 F., lbs 2, 2002, 450 Marshall Flow 140 F., .01 9

1 ASTM D 1559-62T.

Example 3 1 from both the' foregoing asphalt plastisol and thenonplastisol asphalt. The test results for test specimens containing 6.5wt. percent of the plastisol or nonplastisol and 93.5 wt. percent of anAsphalt Institute type VI aggregate are given in Table III and againshow that this invention affords a method for substantially improvingthe fluidity of asphalt without adversely affecting the performancecharacteristics of the asphalt.

TABLE IIL-MARSHALL TEST l Binder Used Nonplastisol Asphalt AsphaltPlastisol Voids, percent 4. 0 4. 5 Marshall Stability F., lbs...-- 1,500 1, 425 Marshall Flow 140 F., .01" 11 12 1 ASTM D l559-62T.

It is not intended to restrict the present invention to the foregoingexamples but rather it should be only limited by the appended claims.

What is claimed is:

1. An asphalt plastisol comprising nonvolatile petrolene particles,having an initial atmospheric boiling point within the range of 600 and1400 F., passing a number 8 US. Sandard Sieve screen, coated withasphaltenes and suspended in liquid volatile petrolenes having a boilingpoint range below that of the said nonvolatile petrolenes, said asphaltplastisol being comprised of from about 10 to about 50 wt. percent ofsaid nonvolatile pertolenes, from about 5 to about 40 wt. percent ofsaid asphaltenes and from about 20 to about 60 wt. percent of saidliquid volatile petrolenes.

2. An asphalt plastisol according to claim 1 wherein the said asphaltplastisol comprises from about 15 to about 30 wt. percent of saidnonvolatile petrolenes, from about 20 to about 35 wt. percent of saidasphaltenes and from about 35 to 50 wt. percent of said liquid volatilepetrolenes.

3. A process for the manufacture of asphalt plastisols which comprisesadmixing asphaltenes and nonvolatile petrolene particles having aninitial atmospheric boiling point within the range between about 600 F.and 1400 F. to form asphaltene-coated nonvolatile petrolene particles,admixing the said coated particles with liquid volatile petroleneshaving a boiling pont range below that of sad nonvolatile petrolenes toproduce an asphalt plastisol comprising from about 10 to about 50 wt.percent nonvolatile petrolenes, from about 5 to about 40 wt. percentasphaltenes and from about 20 to about 60 Wt. percent volatilepetrolenes.

4. A process according to claim 3 wherein the said nonvolatile petroleneparticles have been passed through a number 8 US. Standard Sieve screen.

5. A process for the manufacture of asphalt plastisols which comprises:

( 1) functionating an asphalt comprised of asphaltenes and petrolenesinto (a) a volatile petrolene fraction having an atmospheric boilingpoint below about 600 F. and (b) a nonvolatile fraction comprised ofasphaltenes and nonvolatile petrolenes and having an initial atmosphericboiling point Within the range between about 600 and 1400 F.;

(2) contacting the nonvolatile fraction with a C C normal paraffin toprecipitate the asphaltenes and form an asphaltene fraction and anonvolatile petrolene fraction;

(3) separating said asphaltene fraction from said nonvolatile petrolenefraction;

(4) removing the C -C normal parafiin from the asphaltene fraction andthe nonvolatile petrolene fraction;

(5) cooling the nonvolatile petrolene fraction to a temperature belowabout 60 F.;

(6) pulverizing the cooled nonvolatile petrolene fraction;

(7) admixing the asphaltenes and the pulverized nonvolatile petrolenesto form asphaltene-coated nonvolatile petrolene particles; and

(8) admixing the coated particles with the volatile petrolenes producedin step 1) to form a stable asphalt plastisol consisting essentially offrom about 10 to about 50 wt. percent of said nonvolatile petrolenes,from about 5 to about 40 wt. percent of said asphaltenes and from about20 to about 60 wt. percent of said volatile petrolenes.

References Cited UNITED STATES PATENTS 9/1938 Wells et al. 208-4410/1951 Mollring 208-22 10/1955 Hardrnan 20823 12/1958 Illman 208231/1959 Illman 208-23 7/1959 'Hardman et al. 208-22 1/1963 Corbett 20823DANIEL E. WY MAN, Primary Examiner.

P. E. KONOPKA, Assistant Examiner.

1. AN ASPHALT PLASTISOL COMPRISING NONVOLATILE PETROLENE PARTICLES,HAVING AN INITIAL ATMOSPHERIC BOILING POINT WITHIN THE RANGE OF 600* AND1400*F., PASSING A NUMBER 8 U.S. SANDARD SIEVE SCREEN, COATED WITHASPHALTENES AND SUSPENDED IN LIQUID VOLATILE PETROLENES HAVING A BOILINGPOINT RANGE BELWO THAT OF THE SAID NONVOLATILE PETROLENES, SAID ASPHALTPLASTISOL BEING COMPRISED OF FROM ABOUT 10 TO ABOUT 50 WT. PERCENT OFSAID NONVOLATILE PERTOLENES, FROM ABOUT 5 TO ABOUT 40 WT. PERCENT OFSAID ASPHALTENES AND FROM ABOUT 20 TO ABOUT 60 WT. PERCENT OF SAIDLIQUID VOLATILE PETROLENES.